Abstract 2873: Dual Optical Mapping of Voltage and Calcium Transients in Fruit Fly Hearts
Background Drosophila melanogaster (DM) has a short lifecycle, a fully mapped genome, and is a useful tool to study cardiac genetics. We hypothesize that dual optical mapping can be performed in DM hearts to study the electromechanical (EC) coupling.
Methods DM (N=15) were anesthetized and the hearts were superfused with hemolymph containing blebbistatin, stained with Rh237 and Rhod-2 for dual mapping with MiCAM camera at 100 frames/s and 0.0009 mm2/pixel.
Results We studied 15 hearts with good signal to noise ratio. Typically, pacemaking sites are located at conical chamber (CC) and terminal chamber (TC) (Figure⇓). There are segments with different action potential durations (APD), associated with slowing of conduction from one segment to the next. Other conduction patterns include bidirectional propagation with pacemaker in the middle of the heart (N=1), conduction block in the middle of the heart (N=2) and uncoupled oscillation between adjacent heart segments (N=1). Multiple conduction patterns were observed in the same heart. We measured the APD and the intracellular calcium transient durations (CaiTD) to 90% of recovery. The APD, CaiTDs and conduction velocity (CV) averaged 0.244±0.056 sec, 0.241±0.037 sec and 3.42±0.037 mm/sec, respectively. The APD restitution max slope was 0.39.
Conclusions It is feasible to perform dual mapping of DM hearts, which exhibits multiple competing pacemaker sites, segmental conduction patterns and conduction blocks. The APD restitution slope is positive. Dual optical mapping of the entire DM hearts may be useful in studying the genetic mechanisms of automaticity, conduction disturbances and EC coupling.